1. Field of the Invention
The present invention relates to long (at least C.sub.11) chain .alpha.-acetylenic alcohols as inhibitors of hydrosilylation and to the preparation of stable curable silicone compositions therefrom, preferably of a solvent-free type. These compositions are especially well suited for producing release coatings.
2. Description of the Prior Art
It is known to this art to employ acetylenic compounds such as acetylenic alcohols having a boiling point lower than 250.degree. C., especially 2-methyl-3-butyn-2-ol and ethynylcyclohexanol, as hydrosilylation inhibitors in curable compositions, of solvent-free type, based on an organosilicon polymer bearing olefinically unsaturated substituents (especially of vinyl type), on an organohydrosiloxane polymer and on a catalyst of the platinum or platinum compound type. These compositions can be deposited onto substrates such as paper, for example via coating technique, and can be cured thermally at a temperature on the order of 80.degree. to 250.degree. C., especially from 100.degree. to 220.degree. C., for 3 to 180 seconds (FR-B-1,528,464 and FR-A-2,372,874).
These compositions present the disadvantage, in the case of the preparation of release coatings, of not being capable of crosslinking on the substrate at a temperature of less than 80.degree. C. and of exhibiting an insufficient stability during coating on a machine, gelling of the coating bath already being observed after one hour.
This is due to the fact that these inhibitors can sublime. This major disadvantage requires that they be employed in large amounts, and this results in a marked inhibition of the activity of platinum and, consequently, also mandates the use of a large amount of said catalyst.